Highly Sensitive and Exceptionally Wide Dynamic Range Detection of Ammonia Gas by Indium Hexacyanoferrate Nanoparticles Using FTIR Spectroscopy.

Ammonia gas is useful but caustic; thus, its concentration is monitored depending on applications. We prepared indium hexacyanoferrate nanoparticles (InHCF-NPs, HCF = [Fe(CN)]) with average diameter around 8 nm by simple reaction at room temperature between In cations and HCF anions, and we found the unique functionality of InHCF-NPs which were capable of highly sensitive (16 ppb) and exceptionally wide range (190000, 16 ppb -0.3%) detection of ammonia gas within 6 min by IR measurements. Slope changes of the IR peak ratio of adsorbed ammonium over CN moieties in the InHCF framework indicated a good log-log linear correlation along gas concentrations, in which a wide dynamic range over 10 was realized for the first time in the field of ammonia gas detection.